body,
html {
    margin: 0;
    padding: 0;
    border: 0;
    width: 100%;
    height: 100%;
    font-family: Arial, sans-serif;
    background: lightgray;
}
#iframe {
    display: block;
    height: 100%;
    width: 100%;
    margin: auto;
    padding: 0px;
    border: 0px;
    padding: 0;
}